1. Field
Aspects of embodiments of the present invention relate to a rechargeable battery.
2. Description of the Related Art
A rechargeable battery is a battery that is repeatedly charged and discharged, unlike a primary battery. Low-capacity rechargeable batteries may be used for portable compact electronic apparatuses such as mobile phones, notebook computers, and camcorders, and high-capacity rechargeable batteries may be used as a power supply for driving a motor of a hybrid vehicle, an electric vehicle, etc.
For example, the rechargeable battery generally includes an electrode assembly, a case for receiving the electrode assembly, a cap plate combined to an opening of the case, and an electrode terminal installed in the cap plate and connected to the electrode assembly. The cap plate includes a terminal hole for installing the electrode terminal and a vent hole. The vent hole has a vent plate made of a thin plate with a thinner thickness than the cap plate and is welded to the cap plate to close and seal it.
The rechargeable battery generates internal gas during charge and discharge of the electrode assembly. Also, under an internal short circuit generation of the rechargeable battery, that is, under a short circuit of a positive electrode and a negative electrode of the electrode assembly, heat is generated and an electrolyte solution is decomposed while a potential difference of the charged positive electrode and negative electrode is quickly reduced. When the electrolyte solution is decomposed, a large amount of gas such as methane, hydrogen, or carbon dioxide is generated such that the internal pressure of the rechargeable battery is quickly increased.
Generally, the electrode assembly includes a negative electrode and a positive electrode at respective surfaces of a separator and is formed by winding the negative electrode, the separator, and the positive electrode in a jelly roll state, and has an uncoated region of the negative electrode and the positive electrode where the separator is not interposed. The uncoated region is welded to a lead tab that is compressed and deformed, thereby being electrically connected to the electrode terminal.
The uncoated region blocks the negative electrode, the separator, and the positive electrode from the outside of the electrode assembly, while forming a slant region at the end of the coated region under the compression and deformation. Accordingly, under the internal short circuit generation of the electrode assembly or when leaving the rechargeable battery, the internal gas generated inside the electrode assembly is blocked in the slant region. The dispersion and emission of the internal gas is thereby deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.